Operating cost calculator: diesel or electric?
What does a passenger vessel cost per year in energy and maintenance, with a diesel engine or with batteries? The calculator compares both drives for your operating profile, shows the CO₂ emissions and, if you enter conversion costs, after how many years an electric conversion pays for itself.
How the calculator works
The starting point is the energy the propeller needs per year: operating hours times average propulsion power. For diesel, the specific consumption turns this into litres; for electric propulsion, the efficiency turns it into electricity drawn from the grid. Maintenance per operating hour is added, and for the electric vessel an annual reserve for replacing the battery later: capacity times price divided by service life. Crew, berth, insurance and hull upkeep are not included, because they are similar for both drives.
Why electric is not automatically cheaper
In Germany diesel for commercial shipping is exempt from energy tax.1 At a diesel price of around one euro net, a kWh at the shaft costs about 27 cents; with electric propulsion at 25 cents per kWh and 85 per cent efficiency it costs about 29 cents. The pure energy costs are close. Fuel is in any case only about 15 per cent of a passenger vessel's operating costs.2 The difference comes from the lower maintenance of an electric motor, a cheap electricity tariff or own solar power at the berth, and on the other side the battery, which has to be replaced after ten to fifteen years. That reserve is often the largest single item on the electric side, so it pays to agree capacity, replacement price and service life with the supplier.
Subsidies therefore usually decide the economics. Germany's June 2026 guideline covers up to 90 per cent of a conversion to zero-emission propulsion.3 If a new diesel engine is due anyway, its price counts as an avoided investment against the conversion. With a high subsidy rate the owner's share is small enough to be recovered by a moderate saving. Without subsidies a conversion rarely pays off through operating costs alone; then emission zones, tenders or the passenger experience are the stronger arguments. Background in the article Electrification meets an ageing fleet.
Looking for a vessel suitable for electric conversion, or want to sell your diesel vessel? See current passenger vessels or list your own vessel, with no broker fees.
Frequently asked
Is an electric passenger vessel cheaper to operate than a diesel vessel?
Not automatically. In Germany diesel for commercial shipping is exempt from energy tax (section 27 of the Energy Tax Act). The pure energy cost per kWh at the shaft is therefore often in the same range as with electric propulsion. Savings come mainly from maintenance, cheap or self-generated electricity and subsidies. Against that stands the reserve for replacing the battery later.
How much CO₂ does an electric passenger vessel save?
Burning one litre of diesel emits about 2.65 kg of CO₂. With electric propulsion the emissions depend on the electricity: the German grid mix causes roughly a third of a kilogram of CO₂ per kWh, green power almost none. The calculator shows the difference for your operating profile.
When does a conversion to electric propulsion pay off?
When the owner's share of the conversion, meaning the cost minus subsidies, is recovered through the annual operating cost saving within a reasonable time. Because the saving alone is often small, the subsidy rate usually decides the payback. The calculator shows the years to payback for your figures.
Which figures do I need for the calculator?
Operating hours per year and the average propulsion power in service. Both are usually in the logbook or can be derived from diesel consumption. Realistic starting values are preset for diesel price, electricity price and maintenance; replace them with your own.
Sources
- German Energy Tax Act, section 27(1), tax exemption for shipping (except private pleasure craft). gesetze-im-internet.de
- DNV GL for the German transport ministry, Energieberatung Binnenschifffahrt, short study 2015. dnv.de
- German guideline on grants for green inland shipping of 23 Jun 2026, Federal Gazette 16 Jul 2026 B3; German transport ministry, press release 066, 17 Jul 2026. bmv.de
Note: the calculator gives a rough estimate based on your input. Preset values are typical orders of magnitude, not quotes. It does not replace technical planning or funding advice. Your input stays in your browser and is not transmitted.
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